Process and machine for drying lumber



2 Sheets-Sheet l INVENTOR ATTORNEY Aug. 20, 1929.

` E. w, FowLER PROCESS AND MACHINE FOR DRYING LUMBER Filed Aug. 22, 1924 Aug. 20, 1929.

E. w. FowLER 1,725,708

PROCESS AND MACHINE FOR DRYING LUMBER Filed Aug. 22, 1924 2 Sheets-Sheet 2 Cil Patented g. 20, 19u29.

UNITED STATES ELIHU W. IEOWLER, 0F NEW YORK, N. Y.

PROCESS AND MACHINE FOR DRYING- LUMBER.

Appiication sied August 22, 1924. serial No. 733,502.

Approximately sixty per centum. of all the lumber cut in the United States is fourquarter or inch stock. Heretofore most of this lumber has been either air dried while stacked in a yard or under cover with spacers at vintervals between each layer of boards to permit air circulation or in stationary dry kilns wherein it was also stacked with spacers at intervals between each. layer of boards. lVhen either of these processes is practiced a large percentage of the lumber so dried is lost due to degrade, warping, splitting, checking, etc.

The object of my invention is to provide a continuous quick diying process during which the lumber while being dried is prevented from warping, curling or twisting and toso treat the lumber during the drying process as to prevent so far as possible the enormous losses which occur where lumber is dried by the methods heretofore in use.

My process and machine is primarily designed for the treatment of lumber green from the saw. The length of my machine is dependent upon the character and thickness of the lumber to be dried. I first place the lumber between the feed rolls of my continuous drying machine, the 'pressure of the rolls being suticicnt to prevent. warping, curling or twisting. Immediately after the lumber enters the drying machine I treat -it to a steam bath for the purpose of opening the pores so that the sap and other moisture may more readily be extracted therefrom. lWhen the lumber enters the steaming section of my dryer it is at atmospheric temperature and far below the temperature of the atmosphere within the steaming section of the dryer, which causes moisture to condense upon its surface, the condensation depending upon the temperature of the lumber and the .moisture content of the atmosphere in said steaming section. y regulating the quantity of steam admitted to the steaming -section I am able to regulate the condition of the lumber discharged therefrom. lVhile passing through the steaming sect-ion the temperature of the lumber is .gradually raised until when it passes into the first drying section itis .sufficient to pre-vent further undue condensation. As the lumber passes through the drying section of my machine itis subjected to contact with currents of het air which pass and re-pass over its surfaces and not. only take up moisture on the surfaces of the lumber but gradually raise its temperature to a point above the temperature at which the liquid content of the wood is rapidly volatilized. The surfaces of certain woods tend to case harden when subjected to a high temperature during the drying proc-V ess andthe pores to contract until "it becomes difficult to drive off any further moisture. This causes the lumber to check if the drying process is continued while the lumber is in this condition. lVhen and Wherever there is a tendency to case harden as lumber is passing through the machine I introduce steam in quantity -suiiicient to check this tendency and again open up the surface pores and repeat if and ,as required until the lumber is discharged. I vary the speed of travel of the lumber and the temperature to suit the condition, character and thickness of the lumber being dried and by so doing am able to discharge lumber of varying character and thickness from the drying chamber with the desired moisture content.

My improved drying machine with which I practice my process is illustra-ted in the accompanying drawings in which Figure li is a diagrammatic elevation broken into sections, the length of the dryer as compared with its other dimensions being too great' `to illustrate by a scale drawing without undue reduction. Figure 2 is1 a diagrammatic plan `View of my machine broken into sections. Figure 3 is a section on line 3 3 of Figure l. Figure 4 is an enlarged section of the feeding rolls, steam pipes and heating pipes partly broken away. Figure 5 is a section on the line 5 5 of Figure l and Figure G is a sectional view on the line 6 6 partly broken away. Similar numerals refer to similar parts throughout the respective views.

My dryer 1 is mounted on supporting foundations 2 preferably constructed of reinforced concrete. Upon the inner surfaces of these foundations and spanning the interval between them I place suitably insulat-ing materia-l 3. Laid upon the foundations 2 are channel irons 4 in which, placed at suitable intervals, are rolls 5 upon which are mounted I beams 6, the rolls being for the purpose of permitting movement on the foundation without undue friction and "strain to compensate for contraction and expansion. The I beams are secured together by cross tie members 'i'. At suitable interllt) vals supporting brackets 8 are secured to the I beams 6 and serve as supports for the plates 9. On the plates 9 are mounted channel irons 10 in which are supported side panels 11 preferably of suitable insulating material, secured in position by latches 12. Secured to the I beam 6 are cast iron bearing cages 13. Channel irons 14 extend the full length of the machine and are secured to the upper surface of the bearing cages. Supporting members 15 are 'secured to cross tie members 16. Secured to their upper ends are cross tie members 17 which serve as supports for the roof which is preferably composed'of sheet metal 18 and sheets of insulating material 19. The sheet metal number 18 and sheets of insulating material 19 forming the roof may be secured in position in any suitable manner. I provide a floor 20 of sheet metal which with the top and sides form a long rectangular chamber D extending from end to end of my machine. AMounted in the bearing cages l13 are rolls 21 and 22 disposed in pairs at successive elevations vertically one above another. rihe rolls 21 of each pair are preferably mounted in antifriction bearings 23 while the upper rolls 22 of each pair arefree to move toward or away from the driving rolls 21 within the limitation of the slots 24 in the cages 13. The rolls 21 are provided with sprockets 25 and are driven by a chain 26 driven from any suitable source of power not shown. Chain guides 27 are secured to the cages 13 and serve to prevent the chain from jumping from the sprockets 25. The upper rolls 22 are of suitable weight to bear upon the material being dried with suiiicient pressure to prevent warping, curling or twisting. The spacing of these pairs of rolls longitudinally may be varied according to the character and length of the material to be dried. Supports 28, the ends of which are supported in sockets 29 in the cages 13 and the cross members 7 supported upon I beams 6, serve as supports for the gangs of steam pipes 31. |Ihese gangs of steam pipes collectively extendv longitudinally the full length of the chamber D. Decks of pipes 31 are arranged above, between and below each of the pairs of conveying rolls. Steam of the desired temperature and pressure :is cir` culated through the pipes 31 from a source of supply not shown. The` quantity of steam supplied to the pipes` 31 may be regulated in any suitable manner as by a valve 31a. I also provide gangs of steam pipes 32 which extend laterally across the chamber D- above and below the lumber conveyed by each deck of rolls. Steam is supplied from any suitable source to these pipes by a pipe 33. The amount of steam supplied may be regulatedor cut oif by a valve 34. These steam pipes are provided withy vents 35 from which steam may be jetted as shown in Figure 4 against the upper and lower surfaces of the lumber L which is conveyed by thev vals longitudinally of the chamber D I supf ply mechanism for circulating heated air through the corresponding sections of the chamber D, each circulating mechanism being a duplicate of the other except the circulating mechanism employed in the first or steaming section located atthe entrance end of chamber D, the circulating mechanism of which I will now describe.

In the base or iioor of the chamber D and relatively near the entranceI end thereof I provide a discharge orice 436 which communicates with a discharge conduit 37\ suitably supported from the cross members 7 and floor 20. The conduit 37 discharges into the conduit 38. A.' fan 39 draws the hot damp air through the orifice 36, conduits 37 and 38 through the heater 40 and returns it at the proper temperature through the conduit 41 branch conduits 42 and drop conduits 43 and discharge orifices 44 to the initial or steaming sections of the' chamber D. The drop branches 43 are staggered on each side with reference to` the drop branches on the opposite side and the discharge orifices so arranged that hot damp air is forced diagon. ally across the upper and lower surfaces of the lumber L passing therethrough. This steaming section is partially cut ofi' from the balance of the chamber D by flexible baiiies 46 which press against the lumber and serve to prevent the hot moist air within this section from passing freely to the adjacent .section of the chamber D. Similar baies 46 are employed to seal the entrance of the steaming section. Steam pipes 31 through which I pass steam at the proper" temperature tend to maintain'the atmosphere within the steaming chamber at a proper temperature. i i

`I will now describe the mechanism for circulating hot air in the heating section H which is adjacent to the steaming sect-ion S.

In the ioor 20 I provide a discharge orifice 48 relatively near the entrance end of said section which communicates with a discharge conduit 49 supported from the cross members 7 and the floor 20. This conduit discharges into a conduit 50. A fan 51 eX- hausts the hot` moist air through the orifice 48 and conduits 49 and 50 and causes it to pass through the heater 51a from whence it -57 provided with batlies 58 so arranged that a current or hot dry air is forced diagonally across the upper and lower surfaces of the lumber passing through this section.

The drop branches on each side are staggered with reference tothose on the other side which causes the hot dry air to travel diagonally from one side of the chamber to the other with a gradual iow toward the discharge orifice 48 and in a. direction opposite to the travel of the lumber.

In this and the other heating sections I reduce t-he number of the steam pipes 32 and inject steam from these pipes only when necessary to prevent the lumber from case hardening. I have shownthe circulating mechanism just described duplicated in an adjacent heating section H extending to the discharge end of the chamber. I duplicate the circulating mechanism and pipe gangs as required by the 'length of the chamber D and the character of the lumber which the machine is designed to dry.

I practice my process and operate my dryer as follows:

The lumber to be dryed is introduced between the rolls at the entrance end of the dryer. Air is exhausted from the steaming section S through the discharge orifice 36 and conduits 37 and 38, by the fan 39,

passed through the heater 40, where it is heated to the desired temperature and then returned through conduit 41, branch conduits 42, drop conduits 43 and discharged into the steaming section S through discharge orifices 44 traveling diagonally across the surfaces of the lumber and from one side to the otherof the steaming section S and gradually, toward thedischarge orice 36. During its travel its temperature is maintained by the steam pipes 31. Steam fro-m the pipes 32 is jetted from the vents 35 against the upper and lower surfaces of the lumber in quantity sufficient to thoroughly open the pores thereof. The baffles 46'prevent undue escape of hot moist air from the steaming section VS.

When the lumber is conveyed bv the rolls from the steaming section Sl into the drying section H it has been heated to a temperature 'which will prevent further undue condensation of moisture on its surfaces.

- 'Ihesurfaces of the lumber are then thoroughlv moistened and its pores are open so VThe circulating mechanism exhausts the hot moist air from heating section H, passes it through the heater 51a and then discharges lit into the atmosphere. The circulating mechanism draws fresh air through the heater 51a, where it is initially heated by the hot moist exhaust air, passes it through the heater 53 by which it is heated to the desired temperature and delivered to the section H,- as before described. I have shown the fans and heaters diagrammatically as they may be of any well known commercial type.

If the surfaces of the lumber show a tendency to case harden while passing through this section H, I jet steam upon the surfaces thereof from the pipes 32 in quantity sufficient to correct the tendency. The treatment of the lumber in the subsequent heating section H', and sect-ions subsequent to H if any, is the same as in the heating section H.

As the lumber passes slowly through the heating sections it is heated to a temperature sufficient to volatilize and drive off its moisture content which is absorbed 'bv' the hot dry air. The length of each heating section is such that the hot air circulated through such section will be discharged before it absorbs an undesirable moisture content.

The gangs of steam pipes 32 in the heating sections by which steam may be jetted against the surfaces of the lumber to check the tendency to case hardening are preferably located adjacent to the discharge .ends of t-hese sections, toward which the hot air is traveling, in order to prevent the entire atmosphereof these sections from acquiring an undue moisture content and to localize the steam in the discharge end of the heating section. By providing heating sections with separate individual circulating mechanism, separate individual gangs of heating and steaming pipes, I in effect separate the Ichamber D into sect-ions in which the treatment of the lumber being conveyed through said chamber D may be varied at will to suit the varying condition of the lumber during the drying thereof. By varying the temperature a'nd volumeof the hot air delivered to the heating sections and the rate of travel of the lumber through the chamber D and 'by injecting steam Whenever there is a tendency to caseharden I am able to discharge the lumber with the desired moisture content.

I claim:

1. A machine for drying lumber compris"- ing in combination ak chamber long relatively to its width and height,.means for continuously and individually moving individual pieces of lumber with a constant uninterrupted progressive movement through said chamber, a steaming section at the entrance end of said chamber, means for exhausting a1r from sa1d steamlng section at a for reheating and Yrecirculating such. exhaust l point relatively near the end thereof; means CII air through said steaming section and toward the exhaust end thereof, means for injecting steam into said steaming section, a heating section and independent means for exhausting air from' said heating section at a point relatively'near the end thereof, and means for heating and circulating fresh air through said heating section and toward the exhaust end thereof.

2. A machine for drying lumber comprising in combination a chamber 'long relative to its Width and height, means for continuously and individually moving individual pieces of lumber With a constant uninterrupted progressive movement through said chamber, a steaming section at the entrance end of said chamber, means for exhausting air Vfrom said steaming chamber at a point relatively near the entrance end thereof,

means for reheating and recirculating such heated air diagonally across and toward the entrance end of said steaming section, means for jetting steam into said steaming section, subsequent heating sections each provided With individual and independent means for heating and circulating fresh air through such sections from the discharge toward the entrance ends thereof and exhausting the air at a point relatively near the entrance ends thereof respectively. f

3. A machine for drying lumber comprising in combination a chamber long relative to its Width and height, decks of rolls by which the lumber is continuously conveyed through said chamber, a` steaming section near the entrance end of said chamber, means for exhausting, heating and recirculating air diagonally across said steaming section to- Ward thel entrance end thereof and over .the surfaces of the lumber, means Within said steaming section for jetting steam against the surfaces of the lumber, flexible baffles, adapted to seal the entrance and exit ends of said steaming chamber, subsequent heatj ing sections each provided With individual means for heating fresh air and circulating such heated air diagonally over the surfaces of the lumber toward the entrance lend of such heating sections and means for exhausting the air from. said heating sections at a point relatively near the entrance end of such heating sections. e

4. Alumber drying apparatus comprising in combination with a chamber, means for continuously advancing individual pieces of lumber individually therethrough with an uninterrupted progressive movement, so that the individual pieces are always in continuous motion from the green state to the ultimately desired' state ofl dryness, means in one section of said chamber for treating theindividual pieces oflumber individual-ly to the action of a pore'opening medium,

vidual pieces of lumber individually to circulated hot dry air, and means for further treating the individual pieces of lumber to the action of a pore opening medium Whenever the surfaces of the pieces of lumber require such treatment.

5. The methodeof drying lumber, which consists in continuously advancing individual pieces thereof With an uninterrupted progressive movement, and in preventing checking of the lumber by subjecting the same in its individual pieces to an initial and repeated. pore opening action, and in further subjecting the individual pieces to a circulation and recirculation of air to effect the drying. I

6. The'method of drying lumber by a continuous process which comprises keeping individual pieces of lumber in continuous advancing movement during the entire process and While said individual pieces are being thus continuously advanced and in motion subjecting each individual piece individually to a poreopening treatment and each piece individually to a drying treatment to thereby uniformly treat all the pieces internally and externally.

7. The method of drying lumber by a continuous process `Which consists in continually and uninterruptedlyadvancing the lumber so as to keepv the lumber in continuous motion at all times during the treatment, and in subjecting individual pieces of the lumber individually to the action of a pore opening medium While the lumber is moving with the aforesaid continuous movement.

8. The method of drying lumber which consists in continually advancing individual lpieces of lumber With an uninterrupted progressive movement to maintain motion of the pieces of lumber at all times during the process, and in subjecting the individual pieces individually during their uninterrupted advance and While they are moving individually to -a pore opening action to prevent checking of the lumber, and in also subjectinothe individual pieces of lumber during their continuous advance and While they are moving toa circulation of air to dry the same after the pores are opened.

9. A lumber drying machine for lumber of commercial thickness comprising in combination with one or more drying chambers, a roller conveying system for transporting therethrough, While the lumber is being dried, individual pieces of lumber of commercial size and in spaced relation to each other, and having provisions cooperating With the said individual pieces of lumber to prevent twisting and warping of the lumber during-its continuous transportation through the machine, and means individually cooperating with each individual piece of means for subsequently treating the indi-'vy lumber for preventing checking of the indiioo vidual pieces of lumber during their advance and while they are iii continuous motion by the conveying system.

10.' The method of drying commercial lumber which comprises continuously moving pieces of lumber of commercial thickness from a green state to the desired state of dryness, subjecting all the individual pieces individually while in motion to the same pore opening and drying action, and in restraining the tendency of the individual pieces of lumber individually against warping, twisting, checking and splitting whilelthe lumber is in motion dur-ing 'its treatment.

11. The method of drying lumber of conimercial size which consists in advancing the lumber in individual pieces and with a continuous movement so that each piece constantly moves as it is being dried from a green state to the desired degree of dryness, and while the pieces areindividually moving subjecting the individual pieces individually to an initial and repeated pore opening action, and drying the individual pieces individually While they are in motion.

12. A lumber drying machine having in combination, means for continuously advancing the lumber through the machine with an uninterrupted progressive movement so that the lumber is always in motion from thev time it is entered into the apparatus until it has completed its treatment and means foi' uniformly drying said lumber both internally and externally, said means including a co-acting steaming means for opening the surface and internal pores of the lumber to permit the internal moisture to be extracted, the aforesaid steaming and drying means having provisions so constructed as to cause individual pieces of lumber to be subjected individually to both a steamingand drying action.

13. rIhe invention set forth in claim-12l in whichV means is provided for varying the degree of dryness desired.

14. In a lumber drying machine having in combination with a pore opening means and a subsequently acting drying means, rolls for advancing the lumber through the niachine, said rolls being disposed to each other and to the lumber being dried to receive the lumber therebetween to prevent warping, twisting, splitting and bending of the lumber, the aforesaid pore opening means including means to individually jet each individual 'piece of lumber which is being transported through the machine directly with the pore opening medium whereby each piece irrespective of its location receives the direct action of the pore opening medium.

15. A lumberv drying machine having in combinationl with a pore opening and drying means for the lumber, means for continuously advancing the lumber through the machine and past said means so that the lumber is always in motion from the time it is entered into the machine until it leaves, means for controlling the pore opening and drying means to vary the vdrying laction thereof, said pore opening means having provisions for jetting steam directly upon both surfaces of an individual piece of lumber that is passing through the machine.

16. A lumber drying machine in combination with a pore opening chamber, a drying chamber and conveyor rolls for continuously transporting individual pieces of commer'- cial lumber therethrough, said rolls being disposed and related to receive and guide individual pieces of lumber through the apparatus and to present the individual pieces of lumber individually to the action of a pore opening medium which is supplied in the pore opening chamber and individually to the action of the drying air which is sup'- plied in the drying chambenthe aforesaid drying chamber having means for so directing the air upon the individual pieces of lumber that each piece can receive a dryingA action.

17. A lumber drying machine having in combination means for continuously advancing the lumber through the machine'with an uninterrupted progressive movement so that the lumber is always in' motion from the time it enters the machine during its treatment and until it leaves the machine, means for uniformly drying the lumber both internally and externally, said means including provision for directing drying air edgewise with respect to thevlumber which passes through the apparatus so that allindividual pieces of lumber will be individually accessible to the drying airand also including a coacting steaming means for subjecting the individual pieces of lumber both at t-he top and bottom surfaces of cach individual piece to the action of a poreV opening medium so that checking of the lumber is prevented upon both vsurfaces while it is being continuously advanced.

18. A lumber drying machine including roll-,like conveying means for individually transporting individual pieces of lumber through the machine in spaced superimposed vertical relation to each other, a pore opening chamber and means disposed between the superimposed spaced individual pieces of lumber for jetting the pieces which are vbeing conveyed, each individually with a pore opening medium whereby individual pore opening treatment'may be afforded to the individual pieces.

19. A lumber drying machine comprising an extended chamber, one portion of which comprises an initial pore opening chamber and the other portion of which comprises one or more drying chambers, means for individually conveying lindividual pieces of lumber by rolls continuously with an' unindividually subjecting the pieces of lumberv to the action of a pore opening medium, said means also allowing the pore opening medium to act directly upon its admission directly upon the individual pieces of lumber which are being transported.

20. A lumber drying apparatus including in combination, a plurality of superimposed rollers With means for driving the same to carry in several vertical superimposed spaced layers of individual pieces of lumber through the apparatus, a housing therefor, means to individually subject individual pieces of lumber to the direct individual action of a pore opening medium'in desired parts of ysaid chamber, and meansl for alsol individually subjecting the pieces of lumber y to action of drying air so supplied that the individual pieces receive the effect of the incoming blasts of the drying air. s

2l. A lumber drying machine with rollers for conveying lumber in individual pieces with a continuous uninterrupted progressive movementr therethrough, and means comprising steam jets disposed at each side of an individual piece of`lumber for subjcting both sides of such individual piece which is being advanced by the rolls to the action of a pore opening medium.

22j A lumber drying machine with rollers for conveying lumber in individual pieces with a continuous uninterrupted progressive movement from the time the lumber enters the apparatus until it leaves said apparatus, and means for directing a blast of dryino' air across the lumber from its edges whereby the individual pieces .of lumber Which are carried by the rolls may receive such air by a sweepingVI flow across the surface of suchpieces.

23. In a lumber drying machine includ- `ing a housing which forms a pore opening chamber and one or more drying chambers', rollers for individually carrying pieces of lumber therethrough in spaced vertical relation With iespect to each other, means for subjecting the individual pieces lof lumber to a pore opening treatment which is individual to each piece so that all pieces receivea pore opening treatment and so that all pieces are prevented from checking, and

means for applying drying air to the indi vidual pieces of lum r.

24. The invention set forth in claim 23 in' which means is provided for effecting a circulation and recirculation of moisture laden air in the initial part of the apparatus .for the purpose described.

Q5. The invention set forth in claim *23 inv which means is provided for removing moisture laden air and wholly discharging it out of the apparatus after the individual pieces of lumber have been subjected to an initial pore opening treatment. I

26. The invention set forth in claim 23 'in which means is provided forl withdrawing heated moisture laden air from one part of the apparatus and in which supplemental 1means is providedL for utilizing the heat of such moisture laden air to heat other air which is admitted'into the apparatus for drying the lumber.

ELIHU W. FOWLER. 

